Tar-Ciryatan was the twelfth King of Númenor. He succeeded his father, Tar-Minastir and it was said that he might have persuaded him to do so against his will.

With a great fleet of royal ships he traveled to Middle-earth, bringing numerous treasures back to Númenor. Though a powerful king, Tar-Ciryatan oppressed the men of Middle-earth and scorned his father's yearnings for an alliance with the Eldar. It was during his reign when the Númenoreans began to speak openly against the Ban of the Valar. Those were considered the first signs of the Shadow's passing over Númenor.

The Complete Guide to Middle-earth incorrectly states the year of his death as S.A.2251. This is because in the Tale of Years, it said in that year "Tar-Atanamir takes the sceptre". However, Atanamir died in 2221. 2221 is itself an emendation of 2251, and the former (2221) appears in the later tables, while the latter (2251) in the earlier tables: therefore 2251 (properly 2221) should have read "Death of Tar-Atanamir. Tar-Ancalimon takes the sceptre".[4]